AU2016250363A1

AU2016250363A1 - Cooling device with multiple temperature zones

Info

Publication number: AU2016250363A1
Application number: AU2016250363A
Authority: AU
Inventors: Emanuele Diana; Jochen Ganz; Adrian Hermann
Original assignee: V-Zug AG
Current assignee: V-Zug AG
Priority date: 2015-11-09
Filing date: 2016-10-26
Publication date: 2017-05-25
Also published as: CH709751A2; CH709751A3; EP3171105A1; EP3171105B1; CN106679272A; CN106679272B; CH709751B1

Abstract

Abstract In a cooling device the usable space (1) is divided into two temperature zones (2, 3), wherein a 5 higher temperature should be maintained in the upper tem perature zone (3) than in the lower. Furthermore, air transport means (10, 11, 12, 13) are provided in order to feed air from a cooling module (8) from the bottom into the usable space (1) and to extract from the usable space 10 (1) from the top and to return to the cooling device (8). The controller (14) of the device is adapted to maintain a first set temperature in the lower temperature zone and a second set temperature in the upper temperature zone, and indeed that it chooses (a) the flow velocity of the 15 air transported by the air transport means (10, 11, 12, 13) and (b) the temperature of the cooling module (8) de pending on the desired temperatures in the temperature zones. 20 (Fig. 1) x2 18d 3 x1 12-- |Fig. 1 22 - T2----.------- .----- --- -- 20 - - - T1- 21 X1 x2 Fig. 2

Description

Australian Patents Act 1990 2016250363 26 Oct 2016

ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT

Invention Title

Cooling device with multiple temperature zones

The following statement is a full description of this invention, including the best method of performing it known to me/us:-1

Technical Field 2016250363 26 Oct 2016

The invention relates to a cooling device, in particular a refrigerator or a freezer, according to the 5 preamble of claim 1, and a method for operating such a cooling device.

Background Art 10 It is known to divide the usable space of a cooling device, in particular a refrigerator, in multiple temperature zones, for example in a lower temperature zone and an upper temperature zone. Different set temperatures are provided for these temperature zones, for ex-15 ample 0 - 2°C for the lower temperature zone and 4 - 6°C for the upper temperature zone. In this way, articles can be stored in the lower temperature zone, which should be stored relatively cool, like for example meat, while articles can be stored in the upper temperature zone, which 20 should not be stored quite as cold, like for example cheese.

Furthermore, devices are known, in which cooling air is circulated between a cooling module and the usable space. If such devices should be provided with 25 two temperature zones with different temperature, separate air supplies into the individual zones or additional, individual controllable cooling means are required.

Disclosure of the Invention 30

It is the objective to provide a device of the type mentioned at the beginning, which has a simple structure.

This objective is solved by the device ac-35 cording to claim 1. Accordingly, the device has the following components: la - A usable space with at least a lower and an upper temperature zone: The usable space serves for receiving the product to be refrigerated. 2016250363 26 Oct 2016 - A cooling module for cooling the air: This 5 may be an evaporator of a heat pump or the cold side of a peltier element. - Air transport means in order to feed the air from the cooling module from the bottom into the usable space and to extract it from the usable space from 10 the top and to return it to the cooling module: These air transport means comprise e.g. a ventilator and appropriate air channels. - A controller: The controller serves to control the components of the device. It is adapted to main- 15 tain a first set temperature in the lower temperature zone and a second set temperature in the upper temperature zone, this being done in such a way that it regulates the following two parameters dependent on the (measured or estimated) current temperature in the first 20 and the second temperature zone: a) the flow velocity of the air transported by the air transport means and also b) the temperature of the cooling module.

The basis for this invention is that the tem-25 peratures in both temperature zones can be set in wide ranges independent from each other by appropriate choice of both mentioned parameters. This will be described below in more detail.

The invention also relates to a method for 30 operating such a cooling device, at which the current temperatures can be measured in the lower and the upper temperature zone and the flow velocity and the temperature of the cooling module are chosen dependent on the deviation of the current temperatures from the set val-35 ues. 2

Brief Description of the Drawings 2016250363 26 Oct 2016

Further embodiments, advantages and applications of the invention arise from the dependent claims 5 and the following description according to the figures. Thereby show:

Fig. 1 a schematic sectional view through a cooling device,

Fig. 2 the temperature dependent on the posi-10 tion in the usable space for different flow velocities v and start temperatures TO,

Fig. 3 the correction for a too low temperature at position xl and

Fig. 4 the correction for a too low tempera-15 ture at position x2.

Modes for Carrying Out the Invention

The device according to Fig. 1 has a usable 20 space 1 which is at least theoretically divided in a lower temperature zone 2 and an upper temperature zone 3, wherein the lower temperature zone 2 is arranged below the upper temperature zone 3.

The usable space 1 is closed by a door 4 to-25 wards the user side.

Advantageously, the usable space 1 is permeable to air in vertical direction, i.e. that cooling air can rise through the usable space 1 from the lower end of the usable space to the upper end of the usable space. 30 As illustrated, both temperature zones 2 and 3 can be divided from each other by a dividing plate 5 which has at least one air passage opening. Such a dividing plate 5 reduces the temperature exchange between both temperature zones conditioned by diffusion and radiation, 35 but still allows the flow of air from the bottom to the top. 3

The device according to Fig. 1 further has a heat pump comprising a compressor 6, a condenser 7, an evaporator 8 and a (not shown) throttle between the condenser 7 and the evaporator 8. During operation of the 5 compressor 6 the evaporator 8 is cooled and the condenser 7 is heated. 2016250363 26 Oct 2016

Additionally, air transport means are provided, which comprise an air outlet 10 at the upper end of the usable space 1, a transfer duct 11, a ventilator 12 10 and an air inlet 13 at the lower end of the usable space 1.

In the current embodiment, the air outlet 10 at the upper end of the usable space 1 consists of several openings at the top of the usable space which connect 15 the usable space with the connecting channel 11. The air inlet 13 is formed in a similar way by several openings at the bottom of the usable space. The openings of the air outlet 13 and of the air inlet 10 may also be arranged in the area of the edges of the top or the bottom 20 of the usable space 1, respectively, if needed behind appropriate screens.

The transport power of the ventilator 12, i.e. the flow velocity of the air in the usable space 1, is advantageously configured such that the usable space 1 25 is flooded by air in a laminar way, i.e. no swirl of the air occurs in the flux through the usable space 1.

Air can be removed from the usable space 1 at the top by the air transport means, whereafter this air is guided through the transfer channel 11 and the venti-30 lator 12 to the evaporator 8 and cooled there. The air returns from the evaporator 8 back into the usable space 1 via the air inlet 13.

The heat extracted from the system in that way is discharged via the condenser 7 which may be cooled 35 by ambient air (not shown). A controller 14 is provided in order to control the components of the device. It has the required 4 hardware and software components for controlling the system in the way described in the following. 2016250363 26 Oct 2016

The controller 14 preferably has a memory in which set temperatures for the upper and the lower tem-5 perature zone 3 or 2, respectively, are stored. These set temperatures preferably are between 0 and 10°C, wherein the set temperature for the lower temperature zone is lower zhan for the upper temperature zone, in particular by at least 1°C. 10 The controller 14 can further have input means (not shown) which allow the user to provide one or both of these set temperatures, wherein the controller 14 should ensure in this case that the set temperature for the lower temperature zone is lower than for the upper 15 temperature zone, again in particular at least by 1°C.

Furthermore, two temperature sensor 17 and 18 are shown in Fig. 1. The first temperature sensor is arranged at a height xl in the lower temperature zone 2 and the second temperature sensor 18 is arranged at a height 20 x2 in the upper temperature zone 3.

If the air cooled by the evaporator 8 flows through the usable space 1 from the bottom to the top in direction x, it heats up. In a state of equilibrium the device, the heating is explained by the air which is 25 heated at the side walls of the usable space because the isolation of the usable space is not ideal.

It can be shown that the temperature T(x) can be estimated as a function of the position x (i.e. of the vertical position in the usable space 1) in the state of 30 equilibrium the system by ignoring the heat exchange via diffusion and radiation and by assuming a constant density of the air, approximately by the following relationship: 5 Τ(χ) = (TO - U) · exp(-k·x/v) + U (1) 2016250363 26 Oct 2016

Thereby, TO is the temperature at the lower end of the usable space, U the ambient temperature, k a 5 constant proportional to the thermal conductivity of the side walls and v the flow velocity of the air in the usable space 1.

In the following, the temperature TO also stands for the start temperature and for the sake of sim-10 plicity it is equated with the temperature of the evaporator 8 or the cooling module, respectively.

As can be seen from equation 1, the temperature of the air in the usable space 1 increases from the bottom to the top. The velocity of the increase is sub-15 stantially given by the flow velocity v of the air, while the start temperature TO substantially corresponds to the temperature of the evaporator 8. Both parameters can be varied by the controller 14: - The (averaged) flow velocity v can be var-20 ied by varying the rotational speed of the ventilator 8 or by operating the ventilator with an appropriate on/off relation clocked in short intervals. - The (averaged) start temperature TO can be varied by varying the power of the heat pump or by oper- 25 ating the compressor with an appropriate on/off relation clocked in short intervals.

Fig. 2 shows the course of the temperature T in the usable space 1 as a function of the height position x. Thereby, the curve 20 shows the temperature 30 course for a given start temperature TO and a certain flow velocity v.

Now, if the flow velocity v is increased but the start temperature TO is kept constant, then the curve runs less steep (see curve 21). But if the flow velocity 35 v is reduced at a constant start temperature TO, then the curve runs steeper (curve 22). 6

However, if the flow velocity v is kept constant and the start temperature TO is reduced, then basically lower temperatures result in the cooling room (curve 23), while higher temperatures result at higher 5 start temperature TO (curve 23). 2016250363 26 Oct 2016

Fig. 2 illustrates that by appropriate choice of the parameters TO and v, the temperatures T1 and T2 in the lower temperature zone 2 or the upper temperature zone 3, respectively, at the positions xl and x2, can 10 substantially be chosen independently from each other by appropriately setting the start temperature TO and the flow velocity v. In other words, for given values T1 = T(xl) and T2 = T(x2) the equation 1 can be solved for the parameters TO and v as far as the conditions given to the 15 person skilled in the art from equation 1 and from the physical laws are met, like for example ΤΙ < T2, T1 < U and T2 < U.

In this way it is possible to reach the two desired temperatures T1 and T2 in the lower and in the 20 upper temperature zone 2 or 3, respectively, by appropriately choosing the power of the ventilator 12 and therefore the flow velocity v and the power of the compressor 6 and therefore the temperature of the evaporator 8 by the controller 14. 25 If for example, as illustrated in Fig. 3, the temperature T2 in the upper temperature zone 3 is correct at the current flow velocity ν' and start temperature TO', but the temperature Tl' in the lower temperature zone 2 is too low, then the controller 14 increases the 30 temperature of the evaporator 8 to a higher value TO > TO', and it also increases the flow velocity to a slightly higher value ν' > v such that the temperature curve starts at a higher value TO but increases less quickly.

But on the other hand, as illustrated in Fig. 35 4, if the temperature Tl in the lower temperature zone 2 is correct at the current flow velocity ν' and start temperature TO', but the temperature T2' in the upper tem- 7 perature zone is too low, then the controller 14 reduces the flow velocity to a value v < ν' (such that the curve is steeper) and slightly reduces the start temperature to a value TO < TO'. 2016250363 26 Oct 2016 5 In this way, rules can be found for changing the values of v and TO for the different scenarios of deviation and/or eguation 1 allows the directly approximate calculation of the appropriate values of the flow velocity v and start temperature TO for given values of the 10 temperatures T1 and T2.

Equation 1 represents a very simple model which can use the controller 14 for the calculation of the temperature curve in the usable space 1 dependent on the flow velocity v and the start temperature TO. There-15 by, the heat conductance value k in equation 1 can for example be fixedly provided by the manufacturer, while the second parameter, the ambient temperature U, is either directly measured with an appropriate temperature sensor or estimated based on the current temperatures T1 20 and T2 at constant flow velocity v and start temperature TO .

The controller 14 can also use a more complex thermal model of the usable space, which e.g. additionally takes into account the thermal masses and current tem-25 peratures of the product to be stored in the lower and in the upper temperature zone as model parameters, and/or also the air density changing with the temperature. In particular, the thermal masses and the current temperatures are part of the model as a priori unknown parame-30 ters. However, they can be estimated by the controller 14 by measurements of the temperatures at the positions xl and x2 as function of time, the flow velocity v and the start temperature TO during operation with equalization calculus (i.e. "curve fitting") and then can be used for 35 a better control of the device.

In other words, the controller 14 can be adapted to use a mathematical model described by parame- 8 ters of the thermal properties of the usable space 1 for choosing the flow velocity v and the start temperature TO. The parameters of the model can e.g. be the above mentioned values of k and/or U and/or the thermal mass 5 and/or the current temperature of the loads and/or the air in the temperature zone. Furthermore, the controller 14 is adapted to measure at least one, preferably several temperatures in the usable space depending on the time, the flow velocity v and the start temperature TO and 10 thereby to determine the parameters of the model. 2016250363 26 Oct 2016

In this way, the controller can estimate which influence changes in flow velocity v and start temperature TO have on the temperature distribution in the usable space 1, which allows to regulate the temperatures 15 in both temperature zones more precisely.

While preferred embodiments of the invention have been described in this application, it is clearly noted that the invention is not restricted to them and may be carried out in other ways within the scope of the 20 now following claims.

The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be tak-25 en as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. 30 Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps 35 but not the exclusion of any other integer or step or group of integers or steps. 9

The reference numerals in the following claims do not in any way limit the scope of the respective claims. 2016250363 26 Oct 2016 5 10

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

1. Cooling device, in particular refrigerator or freezer, with a usable space (1) with at least a lower and an upper temperature zone (2, 3), a cooling module (8) for cooling air, air transport means (10, 11, 12, 13) to feed the air from the cooling module (8) from the bottom into the usable space (1) and to remove it from the usable space (1) from the top and to return it to the cooling module (8) and a controller (14), characterized in that the controller (14) is adapted to maintain a first set temperature in the lower temperature zone (2) and a second set temperature in the upper temperature zone (3) by controlling a flow velocity (v) of the air transported by the air transport means (10, 11, 12, 13) and a temperature (TO) of the cooling module (8) depending on a current temperature in the lower and the upper temperature zone (2, 3).
2. Cooling device according to claim 1, wherein a first temperature sensor (17) is arranged in the lower temperature zone (2) and the controller (14) is adapted to regulate the temperature at the first temperature sensor (17) by controlling the flow velocity (v) and the temperature (TO) of the cooling module (8).
3. Cooling device according to one of the preceding claims, wherein a second temperature sensor (18) is arranged in the upper temperature zone (3) and the controller (14) is adapted to regulate the temperature at the second temperature sensor (8) by controlling the flow velocity (v) and the temperature (TO) of the cooling module (8).
4. Cooling device according to one of the preceding claims, wherein the air transport means (10, 11, 12, 13) have an air inlet (13) at a lower end of the usable space (1) and an air outlet (10) at an upper end of the usable space (1).
5. Cooling device according to claim 4, wherein the transport means are adapted for a laminar flow of air through the usable space (1).
6. Cooling device according to one of the preceding claims, wherein the temperature zones (2, 3) are divided from each other by a dividing plate (5), wherein the dividing plate (5) has at least one air passage opening.
7. Cooling device according to one of the preceding claims, characterized in that the controller (14) is adapted to use a mathematical model of thermal properties of the usable space (1), described by parameters, for choosing the flow velocity (v) and the start temperature (TO), and wherein the controller (14) is further adapted to measure in the usable space (1) at least one, preferably several temperatures depending on the time, on the flow velocity (v) and the start temperature (TO) and thereby to determine the parameters of the model .
8. Cooling device according to one of the preceding claims, wherein the first set temperature is lower than the second set temperature, and in particular wherein the first set temperature is at least 1°C lower than the second set temperature.
9. Method for operating the cooling device according to one of the preceding claims, characterized in that the current temperatures are measured in the lower and the upper temperature zone and the flow velocity (v) and also the temperature (TO) of the cooling module (8) are chosen dependent on a deviation of the current temperatures from set values.